A large bustle pipe extends around the outer periphery of the shaft for the delivery of air from hot blast stoves to the furnace tuyeres. A gooseneck pipe extends downwardly from the bustle pipe to a tuyere stock and a blowpipe connected to each tuyere. It is known that the injection of fuel with the hot blast oxygen enriched air fed through the tuyeres can eliminate a substantial part of the coke to reduce the cost of the charge materials. The fuel may be gaseous, liquid or solid carbonaceous material. It may be injected through a lance extending into the tuyere or the blowpipe, or a lance extending through the tuyere stock into the blowpipe or tuyere.
For example, a number of references disclose injection of fuel into a blast furnace tuyere rather than into a blowpipe connected to the tuyere as in applicant's invention. U.S. Pat. Nos. 966,704; 3,197,305; 3,809,524; 3,856,509 each show a single lance for injection of fuel into a blast furnace tuyere. U.S. Pat. No. 3,833,356 shows a lance extending through a pipe connected to the tuyere for injection of fuel along the longitudinal centerline of the tuyere. U.S. Pat. No. 3,917,243 discloses a plurality of fuel supply passages spaced around the periphery of a supersonic blast furnace tuyere between convergent and divergent portions thereof. Russian patent SU 908,812 shows alternate passages for injection of gaseous fuel to the top of a blast furnace tuyere. Another Russian patent SU 910,769 discloses two gas feed tubes for injection of gaseous fuel to the top and bottom of a tuyere. This reference does not disclose a plurality of lances extending into a blowpipe. The gas feed tubes terminate at the wall defining the passage in the tuyere. SU 522,234 shows a lance for injection of gaseous fuel to the top of a tuyere and a separate lance for injection of solid fuel into the bottom of a blowpipe connected to the tuyere.
Other references do disclose lances or passages for injection of fuel into a blowpipe but not the multiple lances of applicant's invention. U.S. Pat. No. 3,209,810 shows a lance for injection of gaseous or liquid fuel into the top of a blast furnace blowpipe. Japanese published patent application J53,087,908 discloses a tube for flowing oil into the bottom of a blast furnace blowpipe. A separate tube 9 is provided for blowing air containing steelmaking dust into the top of the blowpipe. U.S. Pat. No. 4,700,930 shows a branch connection 8 for injection of solid carbonaceous materials into the top of a nozzle connected to a blast furnace tuyere. In summary, none of the references disclose multiple lances for injection of fuel into a blast furnace blowpipe according to applicant's invention.